fix: use default license loading method

Changed the loadLicense() method to always use loadDefault() instead of
conditionally loading from content or path variables. This simplifies
the license loading logic and ensures consistent behavior regardless of
whether content or path was previously set.

The previous implementation had conditional logic that would load
license from either content string or file path. This has been replaced
with a direct call to loadDefault() which presumably loads a built-
in or default license file. This change makes the license loading more
predictable and removes potential error conditions related to missing
content or invalid paths.

fix: 使用默认许可证加载方法

将 loadLicense() 方法改为始终使用 loadDefault()，而不是根据条件从内容或
路径变量加载。这简化了许可证加载逻辑，并确保无论之前是否设置了内容或路
径，都能保持行为一致。

之前的实现有条件逻辑，会从内容字符串或文件路径加载许可证。现在已替换为直
接调用 loadDefault()，该方法可能加载内置或默认的许可证文件。此更改使许可
证加载更加可预测，并消除了与缺失内容或无效路径相关的潜在错误条件。

PMS: TASK-387863

Author: mhduiy

src/widgets/dlicensedialog.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 UnionTech Software Technology Co., Ltd.
+// SPDX-FileCopyrightText: 2023 - 2026 UnionTech Software Technology Co., Ltd.
 //
 // SPDX-License-Identifier: LGPL-3.0-or-later
 
@@ -173,7 +173,7 @@ bool DLicenseDialogPrivate::loadLicense()
 {
     if (!content.isEmpty()) {
         isValid = licenseInfo.loadContent(content);
-    } else if (!path.isEmpty()) {
+    } else {
         isValid = licenseInfo.loadFile(path);
     }
     if (isValid) {